Inflow Performance Relationships With Inertial Effects in the Reservoir

Abstract

ABSTRACT This work presents results on inflow performance relationships (IPR) under the presence of inertial effects in the reservoir. Both, slightly compressible liquid flow and solution gas-drive systems are considered. Up to date, most of the studies on this area have been directed toward dry gas reservoirs. However, as it is shown in this paper, the presence of non-Darcy flow has a sound effect on inflow performance for reservoirs containing other fluids. Thus, the shape of the IPR curve for a liquid flow system may present a parabolic behavior, similar to the shape of the multiphase IPR curves. For the case of multiphase flow it is illustrated that the value of the exponent "n" in Fetkovich's equation1, is smaller than one when non-Darcy flow effects are important. This observation agrees with Fetkovich1 conclusion based on field data. It is also verified that a cartesian plot, as suggested by Jones, Blount and Glaze2, is useful to detect and evaluate the presence of non-laminar flow. The behavior of the integrand of the deliverability equation suggested by Fetkovich1 is explored under multiphase non-Darcy flow and a new deliverability equation is presented. Synthetic examples obtained with a finite difference black-oil simulator are presented. The numerical model considers a variable bubblepoint formulation, which has important consequences under non-laminar flow, especially on the repressurization effects which influences the rate-pressure behavior. Also, field examples are presented. Different procedures proposed in the literature to predict oil rates are examined under non-laminar flow conditions.